I won't go into details about how the team achieved this level of damage, since that's the whole point of the video. Essentially, though, two teams got together in Warsong Gulch and conspired to apply all the buffs and debuffs possible.
Don't worry about getting hit by a crit of this size in your usual Warsong Gulch gameplay. When you watch the video, you'll see that it took a lot of work and a little luck to make this crit happen.
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